In the past, many structures have been provided to support a vehicle occupant seat and to permit it to be slid forwardly and rearwardly as desired to be locked in different positions to accommodate occupants, particularly drivers of different height and size.
The automotive industry has conventionally adopted mechanisms such as those illustrated in the present inventor's U.S. Pat. Nos. 4,527,767 4,563,044 4,572,469; 4,580,755; 4,588,234; 4,438,898 and 4,487,459. Such mechanisms teach typical seat slides having upper and lower U-shaped tracks with special bearing assemblies typified by U.S. Pat. No. 4,511,187. These mechanisms suffer the disadvantages that they are relatively costly, are relatively heavy and may suffer from failure under collision conditions which would entail the seat structure breaking loose from the vehicle floor.
U.S. Pat. No. 3,120,371 to Dall teaches a seat track mechanism in which a sheet metal support is coupled to the vehicle floor. The support extends from the floor as a planar panel and ends as a formed support tube of cylindrical shape. A split tubular member is disposed coaxially about the support tube and carries brackets for mounting to a vehicle seat. Bearings are provided about the support tube so that the split tubular member is slidable longitudinally on the tube support coaxially therealong. Dall teaches a complex locking system to lock the split tubular member relative to the support tube.
The seat track mechanism of Dall suffers a number of disadvantages. In use of Dall, the occupant seat itself needs to have a support beam to extend longitudinally along top of the split tubular member. This support beam increases the overall weight of the seat system. The mechanism of Dall will disadvantageously become detached from the vehicle seat under failure loading conditions as occur in collisions. Under high loads, the split tube member will readily spread to disengage from about the support tube, whereby the seat will become detached from the vehicle. The locking system has a significant number of parts, is complex, heavy and difficult to assemble.